local-aws-api-gateway

This is a simple tool to emulate AWS API Gateway locally. It supports both REST and Web Socket APIs.

The main goal is let you develop your AWS Lambda functions locally without any dependencies.

Pre-requisites

You have to use ES6 modules in your Lambda functions.

package.json

{
  ...
  "type": "module",
  ...
}
``

Install

npm install --global local-aws-api-gateway

Usage

REST API

Mapping.js

import { handler as helloHandler } from "./Lambda.js";

export const REST_MAPPINGS = [
  {
    method: "GET",
    path: "/hello/{name}",
    handler: helloHandler
  }
];

Lambda.js

export async function handler(event) {
  const name = event.pathParameters.name;

  return {
    statusCode: 200,
    headers: {
      "Content-Type": "application/json"
    },
    body: JSON.stringify({ message: `${name}, Hello World!` })
  };
}

Run

local-aws-api-gateway Mapping.js

Test

Access to http://localhost:8080/hello/John

Web Socket API

Mapping.js

import { handler as wsConnectHandler } from "./WsLambdaConnect.js";

export const WS_MAPPINGS = [
  {
    path: "/",
    handlers: {
      $connect: wsConnectHandler,
      $disconnect: ...,
      $default: ...,
      custom: ...
    }
  }
];

WsLambdaConnect.js

import * as AWS from "@aws-sdk/client-apigatewaymanagementapi";
const client = new AWS.ApiGatewayManagementApi({ region: "REGION", endpoint: "http://localhost:8080" });

export async function handler(event) {
  const connectionId = event.requestContext.connectionId;

  await client.postToConnection({
    ConnectionId: connectionId,
    Data: "Hello World!"
  });

  return {
    statusCode: 200
  };
}

NOTE: You need to set any region and the endpoint must be http://localhost:8080 when you use ApiGatewayManagementApi in Web Socket API.

Run

local-aws-api-gateway Mapping.js

Test

You can use wscat to test Web Socket API.

wscat -c ws://localhost:8080

Both REST and Web Socket API

Mapping.js

export const REST_MAPPINGS = [
  ...
]

export const WS_MAPPINGS = [
  ...
]

Run

local-aws-api-gateway Mapping.js

Use another port

PORT=8888 local-aws-api-gateway Mapping.js

Use your environment variables

.env

DATABASE=localhost
USERNAME=root
PASSWORD=password

Run

local-aws-api-gateway Mapping.js